Fire alarm



Feb. 4, 1936. w, ALE)'(ANDER 2,029,402

FIRE ALARM Filed Dec. 28, 1931 2 SheetsSheet l OOOO 0000 numb Bnventor W v attorney J. W. ALEXANDER FIRE ALARM Filed D80. 28, 1931 2 sneet-sneet' 2 Joly/Y )1. i1. [xi/Akin GttorneQ Patented Feb. I 4, 19 36 UNITED STATES PATENT OFFICE FIRE ALARM John W. Alexander, Clarendon, Va.

Application December 28, 1931, Serial No. 583,561

1 Claim.

The present invention relates to improvements in flre alarms of the portable, electrically operated type, employing a thermostat as a circuit maker for the alarm or signal circuit in which circuit the alarm device is located. While I have here illustrated the alarm as an audible one, or electric bell, it will be understood that a .visible signal or alarm may be actuated when the circuit maker a closed under conditions of excessive heat 10 that actuate the thermostat. By the utilization of my invention I am enabled to produce a selfcontained, compact, portable, and convenient device of this character, which while especially designed to perform the functions of an automatic alarm in a hospital, dwelling, &c., is also adapted, for use in various other buildings or structures,

to sound an alarm when an excessive degree of temperature is reached.

,. The invention-consists in certain novel com- 20 binations and arrangements of parts including a source of electrical energy, as a battery, the electrically operated signal, the thermostat, and connections whereby an eflicient, durable, and convenient device of thisv character is provided.

25 In the accompanying drawings I have illustrated one complete example of the physical embodiment of my invention in which the parts are comblned and arranged according to one mode I have thus far devised for the practical application of 30 the principles of my invention.

Figure 1 is a perspective view illustrating the exterior appearance of the portable device of my invention. Figure 2 is an enlarged vertical section through the outer casing of the device show- 35 ing the parts of the device in sideelevation. Figure 3 is an end view, with the casing removed, looking from the left in Figure 2. Figure 4 is a plan view of the underside of the top of the instrument, separated therefrom for convenience 40 of illustration. Figure 5 is a top plan view of the device with the top removed. Figure 6 is an inner face view of one of the end plates with terminals for the thermostat. Figure 7 is a sectional view showing one of the terminals for the thermo- 5 stat and Figure 8 is a similar .view showing the other terminal and connections for the thermostat. Figure 9 is an enlarged'detail sectional view showing one of the terminal connections for the thermostat.

50 In the portable, self-contained alarm device I preferably employ a suitable battery I that is encased within its holder 2 with the top 'of the battery approximately flush with the open upper end of the holder, while the holder at its bottom is 55 fashioned witha base 3 of suflicient area to provide a stable support for the device which may rest on the floor of a room, or upon any other suitable support. A removable top 4 is provided for the device or instrument, and as shown the top is secured to the battery holder or body of 5 the instrument 2, by screws as 5. a

To protect or shield the instrument or device from breakage of parts, and to present a neat and attractive appearance, I preferably employ a casing 6 that surrounds the operating parts of the 10 device, and screws I at the bottom of the casing may be utilized to secure the open bottom casing to the base 3. A pivoted handle or ball 8 is secured at the top of the instrument for convenience in transportation, or this bail may be used to suspend the alarm device from a suitable support on a building wall.

At the opposite ends of the casing are provided reticulated or perforated portions 9 for the purpose of permitting access of the atmosphere to the thermostat within the casing, and other perforations ll) permit transmission of sound from the alarm.-

At one end or side of the holder 2 is attached a bell bracket II, by means c. bolts l2, and the bell l3 with its tapper It may beof any well known electro-magnetically operated type with a customary magnet located in the magnet casing 15.

Two terminal bolts l6 and i1 are provided for 0 v the bell, and as seen in Figure 5 these bolts have mounted thereon terminal posts l8 and I9 fashioned from copper plate and clamped on the bolts in secure manner.

The battery I is provided with the usual terrninal posts 20 and 2|, the former at thecenter and the latter at the side of the top of the battery, as indicated in Figure 5.

The top plate 6 may be fashioned from wood, molded or cast from composition material, or other suitable insulating material may be employed in the manufacture of these top plates, and the conductors for the bell and battery and thermostat are encased in these insulated top plates.

Near one end of the plate two holes 22 and 23 are provided through which, or into which, the two terminal posts l8 and I9 project, and a second pair of holes 24 and 25 are provided in the top plate into which the battery terminals 20 and 2| project when the top plate is in place.

A slot 26 connects the two holes 22 and 24 in the top plate and a conductor blade 21, of resilient, conducting material, is encased within this slot, with its free ends projecting into the holes and in frictional and electrical contact with the respective posts l8 of the bell and 28* of the battery. A second blade 28 is encased in a slot 29, and

a third blade 38 is encased within the slot 3| of the top plate, and these two slots terminate at one end of the plate in socket slots or guide slots 82 that open at the end of the plate. As seen in Figs. 7 and 8 the slots are wider or deeper {than the width of the blades, and the slots, as

. best seen in Figure 4 are arranged in zig-zag form so that the resilient conductor blades will frictionally engage the walls of the slots and hold,

the blade in place, and bridges 33 are provided at the tops and bottoms of the slots to prevent displacement oi the conductor blades.

The resilient ends 28' and 38' of the blades 28 and 38 terminate in the end slots 82, and these guide slots or socket slots receive the blades or prongs 86 and 61 of the connection plug 65, which as indicated in Figure 4 are slid into the slots in frictional and electrical contact with the spring blades to make the connection between the battery and bell and the thermostat.

The thermostat is located or mounted on the side of the battery holder opposite to the bell attachment, and an attaching plate 34 and screws .35 are employed for this purpose.

In addition to the attaching plate 34 I employ the intermediate plate 86,- and an outer plate 31, andthese two plates are secured to the attaching plate by bolts as 38. These three platesand their connections provide a detachable unit for the theribnostat that is combined with the battery and ell.- 1

The thermostat includes the'circular flanged disk 89 that'is spaced from the outer plate3'l, and secured thereto by bolts as 48, and the fiatspring or resilient arm 4| and its coil 42 are secured by the screw 48 to the disk, with a contact-head 44 for electrical connection. For coaction in making the electric circuit with the resilient arm 4|, I employ a stationary, but adjustable blade 45 that projects through an opening 46 in the disk and is located in the path of movement of the arm. It will be understood that .when the. arm 4| and coil 42 are affected by excessive heat, the arm is swung to the right in Figure 3- into frictional and electrical contact with the'blade or contact member 45 to close the signal circuit.

The adjustable contact blade is fashioned with forms the other terminal for the thermostat, andthis screw 58 is secured also in the outer plate 81, by means of a lock nut 5| .and'the screw-head.

The screw 58 is alined with the coil screw 43,

and between the screw 58. and the head 44 is interposed a spring 52 coiled around screw 58 to insure at all times the proper contact for electrical current between the screws 48 and 58. 4

As best shown in Figures 6, 7, and 8, the intermediate plate 38 is provided with a pair of contact blades for connection with the terminals of the thermostat, theresilient or spring blade 53 being-held in contact with the terminal screw 43.

The plate 36 is fashioned with an opening 54 to permit frictional contact between 'the resilient blade and the screw, and the blade is bent or shaped in such manner that it may be secured in two parallel slots 55 and 56 in the intermediate plate. Thus the resilient free end of the blade is located at the outer side of the intermediate plate for contact with the screw head 48'and the plates 38,and 31 are clamped together to insure close frictional contact and similar electrical contact between the screw and blade. A conductor or wire 51 is soldered or welded to the upper end of the resilient blade, and this wire is depressed in a groove 58 in the inner face of the intermediate blade as indicated in Figures 6 and 8'.

A second resilient blade 59 is mounted in the intermediate plate adjacent the complementary hole or orifice 88, and this blade is held in close frictional and electrical contact with the screw- 58 as indicated in Figure 7. YA pair of parallel slots 6] and 52 are provided in the intermediate plate for anchoring the resilient blade 59, and a conductor 84 is welded or soldered to the blade. This conductor is depressed in the zig-zag groove 54 in the inner face of the intermediate blade, and it will be apparent that as the two plates 86v and 34 are clamped together, the conductors 51 and 83 depressed in the grooves provided therefor, are securely anchored and protected against wear or breakage. As clearly'shown in Figure 6 these conductors 51 and 53 are passed through the plug 65 and are then secured to the two prongs or blades 66 and 61 of the plug.

The thermostat unit as'thus described is a compact combination and arrangement of the required parts to insure a simple and inexpensive thermal device, which is attached to-or mounted on the holder 2 by means of the screws 85, and the parts are firmly secured against displacement or breaking, thus substantially avoiding or eliminating' the necessity for repairs. 1

The plug is detachably connected with the top plate-of the device, and it will be apparent that the prongs or blades 86 and Elof the plug 65 may be slipped upwardly into position at the openings of the grooves 33 and 38, and then these prongs are slid along the socket grooves until the prongs slide into frictional and electrical contact with the resilient coils or springs 28 and 38. The prongs are forced between the spring coils and the walls of the socketgrooves into close frictional contact, and the plug with itsprongs is supported by the frictional contact from the top plate. In this manner the electrical connection between the thermal device and the bell and battery is completed and the alarm is set. If desired or necessary to disconnect these parts, the plug is slid to the left in Figure 2 (after thecasing 6 has been removed) thus breaking the circuit, and the plug may hang freely on its cords 51 and 63.

From the above description taken in connection: with my drawings it will be apparent that I have provided a durable, compact, and conveniently arranged instrument for the purpose desired, which is inexpensive in the cost'of manufacture, reliable, and eflicient in the performance of. its functions.

While I have shown one complete example of the physical embodiment of my invention, it will be evident that changes and alterations may be made, within the scope of my claim, without departing from the principles of my invention.

Havingthus fully described my invention, what I claim as new and desire'to secure by Letters Patent is: 1

The combination in a fire alarm with a holder, a battery therein, and an alarm mounted on the holder, of a removable top plate for the holder having holes and open-end slots, terminal posts on the battery projecting into two of said holes and terminal posts of the alarm projecting into two other holes, a resilient conductor blade in one slot having a free end in contact withan alarm terminal and another free end projecting into the open end 0! its slot, a second conductor blade having a free end in contact with a battery post and its other end projecting into the open end of its slot, a thermostat mounted on the holder and a connecting plug electrically connected therewith, blades on said plug for frictional engagement with the ends of the blades in the open end slots, and a third conductor blade in a slot of the top plate having its resilient ends in contact with a battery post and an alarm post respectively. v

JOHN W. ALEXANDER. 

